Mixture of polyamide, polystyrene, and polyamide-styrene graft copolymer



United States Patent 3,334,153 MIXTURE 0F POLYAMIDE, POLYSTYRENE, AND POLYAMIDE-STYRENE GRAFT COPOLYMER Osamu Fukushima, Shigekazu Onishi, Ryuichi Otsubo,

and Hiroshi Hayanami, all of Kurashiki, Japan, assignors to Kurashiki Rayon Co., Ltd., Kurashiki, Japan No Drawing. Filed May 13, 1965, Ser. No. 455,652 Claims priority, application Japan, June 11, 1964,

39/ 32,912 8 Claims. (Cl. 260-857) This invention relates to blended spun fibers consisting of polyamide or a cocondensate consisting mainly of polyamide (A-condensate), and polystyrene or copolymer consisting mainly of polystyrene (B-polymer) by melt spinning, more particularly, to a blended spun fiber consisting of a mixture of at least 20% of the A-condensate and B-polymer manufactured by extruding a melt of a mixture of A-condensate, B-polymer and copolycondensate of polyamide and polystyrene through a spinneret to obtain the blended spun fiber.

At present, researches on polymer blends of various high molecular weight substances have been carried out in the plastic field. Further, the researches have been also made on mixed melt spinning by means of polymer blends in the field concerned.

However, the case of mixed melt spinning, wherein various kinds of high molecular weight substances having different molecular structures are mixed and melted to be spun, is different from the case of plastics because there occur remarkable segregation phenomena between high molecular weight substances so that a simple blending and melting of two or more kinds of high molecular weight substances having different chemical properties, makes the spinning often impossible, more particularly, when the mixture ratio of the two high molecular weight substances becomes mutually very close, the manufacture of molten-blended spun fiber becomes very difficult, and the present inventors have-found that as a special spinning condition that the filament should be cooled down to a temperature within a certain temperature range just after the mixed melt spinning is carried out is necessary to effect a stable spinning.

The inventors have investigated successively various spinning methods for mixed melt spinning conditions which enable more stable high speed spinning and as a result the inventors have found that the spinning stability can be remark-ably improved and the high speed spinning can be attained by mixing part of copolymeric condensate of polyamide and polystyrene, when blended spun fiber consisting of polyamide, or a cocondensate consisting mainly of polyamide (A-condensate) and polystyrene, or a copolymer consisting mainly of polystyrene (B- polymer) is prepared. The invention is based on the following fact:

For example, when a mixture of polyamide and polystyrene is melted at a temperature of 260 to 300 C. in the presence of nitrogen, they are dispersed from each other as very fine particles and exhibit a semitransparent state, whilst if this molten solution is cooled gradually, polyamide and polystyrene are segregated very rapidly and both of these high molecular weight substances are separated into two layers on complete cooling (room temperature). On the other hand, when the melt is quenched, the dispersed state is settled maintaining a relatively good condition.

Such dispersion at a high temperature and segregation phenomena during the cooling step are presumed to be the main cause for making the blending of polyamide and polystyrene impossible.

The inventors have found a spinning condition for enabling stable, high speed spinning based on the prevention of segregation by means of the quenched spinning system as explained above, and further found in estab lishing more stable spinning condition as well as seeking fora method other than the quenching system for solving such troublesome phenomena of rapid segregation of polyamide and polystyrene during the cooling step; and they arrived at the present invention which enables very stable and very high speed spinning by admixing part of a copolymeric condensate of polyamide and polystyrene to a spinning solution consisting of the A-condensate and the B-polymer, then substantially no segregation phenomena of polyamide and polystyrene occur even during the cooling step, but they exhibit a uniformly distributed state, and in case of extrusion of such solution through the spinneret.

As the polyamide to be used in the invention, 6-nylon, 66-nylon, 7-nylon, ll-nylon, 6-l0-nylon, and copolymer of 6-nylon and 66-nylon are enumerated. Further, as the cocodensate consisting mainly of polyamide, polyester amide consisting of e-caprolactam, terephthalic acid and ethylene glycol, where the polyamide component takes more than 60% by weight thereof, are enumerated.

For the graft copolymeric condensate of polyamide and polystyrene to be used in the invention, chemical methods, photochemical method, oxidation method utilizing peroxide, ultraviolet irradiation methods, radiant ray irradiation methods, a method utilizing an initiator of ionic polymerization systems, such as BF AlCl TiCl and A1Br and other various methods capable of forming graft copolymeric condensates are available. For example, a graft copolymeric condensate consisting of 6-nylon and polystyrene where styrene is graft-polymerized with 6- nylon by means of radiant rays, or a graft-polymeric condensate where lactam is condensed with a copolymer of styrene and acrylic acid, and others can be used in the invention.

Further, according to the invention, even if the mixture ratio of copolymeric condensate of polyamide and polystyrene is very small (more or less 1%), its effect can be recognized, and also the graft ratio has similar tendency, and its effect is very remarkable to such a degree that the lower limit cannot be specified. However, the preferable condition would be more than 1 to 2% mixture ratio and more than 5% graft.

In carrying out the invention, the optimum temperature for melt spinning depends upon the kind of the A-condensate and cannot be specified at random. However, such a temperature range of higher by 30 C. than the melting point of the A-condensate to higher by C. than the said melting point is adopted.

A spinning method characterized by cooling down to a temperature in a definite range the filament just after the melt spinning according to the invention can be applied in parallel. There may be a case where the said application Willl be more advantageous, depending upon the mixture ratio of A-condensate and Bpolymer.

Example 1 Nylon 6 (polycaprolactam) was irradiated with cobalt 60 to a total dose of 3x 10% and then was immersed in styrene monomer to effect graft copolymerization with the styrene. The graft polymerization was continued until a graft copolymer of 50% styrene content had been obtained. Five parts of the said copolymer were blended with parts of a mixture of 40% of 6-nylon and 60% of polystyrene and supplied to a screw extruder heated up to 280 C., whereby the mixture was extruded through a spinneret of 350 holes each having 0.25 mm. dia. Very stable spinning was carried out by taking up at a speed of 500 m./minute. On the other hand, when said copolymer was not blended, the filament was often cut off even at a spinning speed of 200 m./minute.

3 Example 2 Two parts of nylon-styrene copolymer used in Example 1 were blended with 98 parts of 50% of 66-nylon and 50% of polystyrene and supplied to a screw extruder heated up to 300 C., whereby the mixture was extruded through a spinneret of 100 holes each having 0.3 mm. dia. Very stable spinning was effected by winding at a speed of 600 =m./minute while blowing air into the filament drawing chamber from the part 10 mm. underneath the spinneret and lowering to 90 C. the temperature of the atmosphere at the part of 5 mm. outside of the filament by 30 mm. lower than the spinneret surface.

Example 3 A mixture of 55% of styrene, 40% of e-caprolactam, 4.5% of acrylic acid, and 0.5% of benzoyl peroxide was heated at 100 C. for 6 hours and then at 300 C. for 6 hours, whereby the graft polymer of styrene and nylon was obtained. Four parts of said copolymer were blended with 96 parts of a mixture of 45% of 6-nylon and 55% of polystyrene and supplied to a screw extruder heated up to 290 0., whereby the mixture was extruded through a spinneret having 100 holes each having 0.3 mm. dia. Very stable spinning was effected by winding at a speed of 700 m./minute while blowing air into the filament drawing part under the spinneret and lowering to 70 C. the temperature of the atmosphere at the part of 5 mm. outside of the filament by 30 mm. lower than the spinneret surface.

What we claim is:

1. A polyamide-polystyrene fiber consisting substantially of 99 to '95 parts by weight of a mixture of 20 to 50 percent by weight of polyamide and 80 to 50 percent by weight of polystyrene, and 1 to 5 parts by weight of a graft copolymer selected from the group consisting of a polyamide-graft-copolymerized with styrene, a polystyrene graft-copolymerized with epsi'lon-caprolactam, and a styrene-epsilon-caprolactam graft copolymer.

2. A fiber according to claim 1, wherein said copolymer is polycaprolactam-styrene graft copolymer obtained by graft polymerizing polycaprolactam with styrene by gamma ray irradiation.

3. A fiber according to claim 1, wherein said copolymer is a graft copolymer consisting of styrene-acrylic 5. A fiber according to claim 1, wherein said mixture consists of 95 parts of a mixture of 40% by weight of polycaprolactam and 60% by weight of polystyrene and 5 parts of copolymer containing by weight of styrene obtained by grafting styrene with the irradiated polycaprolactam.

6. A fiber according to claim 1, wherein said mixture consists of 98 parts of a mixture of 50% by weight of polyhexamethylene adipamide and 50% by weight of polystyrene and 2 parts of copolymer containing 50% by weight of styrene obtained by grafting styrene with the irradiated polycaprolactam.

7. A fiber according to claim 1, wherein said mixture consists of 96 parts of a mixture of by weight of polystyrene and 45 by weight of polycaprolactam and 4 parts of a styrene-nylon graft copolymer obtained by c-opolymerizing 55% of styrene, 40% of e-caprolactam, 4.5% of acrylic acid and 0.5% of benzoylpe-roxide.

8. A composition suitable for the melt-spinning of polyamide-polystyrene fibers substantially consisting of 99 to parts by weight of a mixture of 20 to 50 percent by weight of polyamide and 80 to 50 percent by weight of polystyrene, and 1 to 5 parts by weight of a graft copolymer selected from the group consisting of a polyamide graft-copolymerized with styrene, a polystyrene graftcopolymerized with epsilon-caprolactam and a styreneepsilon-caprolactam graft copolymer.

References Cited UNITED STATES PATENTS 3,088,791 5/1963 Cline 260-883 X 3,134,746 5 1964 Grabowski. 3,218,371 11/1965 Grabowski 260857 3,236,914 2/1966 Murdock et a1. 260-857 3,243,478 3/1966 Seelig 260-857 FOREIGN PATENTS 1,131,883 6/1962 Germany.

872,515 7/1961 Great Britain.

899,567 6/ 1962 Great Britain.

OTHER REFERENCES Review of Textile Progress, vol. 13, 1961, pp. 100- 101, by W. J. Roff.

ALEXANDER H. BRODMERKEL, Primary Examiner.

J. H. WOO, Assistant Examiner. 

1. A POLYAMIDE-POLYSTRENE FIBER CONSISTING SUBSTANTIALLY OF 99 TO 95 PARTS BY WEIGHT OF A MIXTURE OF 20 TO 50 PERCENT BY WEIGHT OF POLYAMIDE AND 80 TO 50 PERCENT BY WEIGHT OF POLYSTYRENE, AND 1 TO 5 PARTS BY WEIGHT OF A GRAFT COPOLYMER SELECTED FROM THE GROUP CONSISTING OF A POLYAMIDE-GRAFT-COPOLYMERIZED WITH STYRENE, A POLYSTYRENE GRAFT-COPOLYMERIZED WITH EPSILON-CAPROLACTAM, AND A STYRENE-EPSILON-CAPROLACIAM GRAFT COPOLYMER. 